In many cases, the surface of plastic products has to be provided with special effects which either can only be produced incompletely, if at all, during molding/shaping for technical reasons or can only be produced unfavorably for economic reasons. One such effect is, for example, improving the softness of the products, particularly in the case of articles which come into direct contact with the human skin.
In the production of hygiene articles, such as diapers or sanitary napkins, and also wiping cloths or “geofleeces”, absorbent materials are used to take up aqueous liquids. In order to prevent direct contact with the absorbent material during wear and to increase wearing comfort, this material is enveloped in a thin water-permeable nonwoven. Such nonwovens are normally made from synthetic fibers, such as polyolefin or polyester fibers, because these fibers can be inexpensively produced, show good mechanical properties and are heat-resistant. With this application in mind, it is also desirable to be able to produce nonwovens with high levels of softness.
Additives of the type in question are generally processed with polyolefin granules to form a masterbatch which is then added as such to the polymer granules before processing to the fibers or other end products, followed by extrusion. However, it is desirable for reasons of cost to be able to incorporate such additives during the actual extrusion process in the extruder.
Accordingly, the problem addressed by the present invention was to provide additives for improving the softness of polyolefin fibers or articles containing such fibers.